556 SPECIAL PHYSIOLOGY. 



ditional fat, whilst the alkaline reaction of bile, even when present, 

 depends probably on phosphate of soda. Experiment shows, however, 

 that the bile is highly important for the proper digestion of fatty mat- 

 ters. In animals with biliary fistulas, the chyle collected from the 

 lacteals, or absorbents of the intestines, contains but a small quantity 

 of fat ; half, or even more, of the fat taken with their food, passes 

 unchanged from the alimentary canal ; and, as a consequence of this, 

 the bodies of such animals are very lean. According to the observa- 

 tions of Blondlot and others, animals thus treated may live even as 

 long as five years. Again, after ligature of the biliary duct in an 

 animal, which prevents the descent of bile into the intestine, the fluid 

 in the lacteals is clear and deficient in fat, instead of presenting its 

 characteristic milky-white color, and fatty molecular contents. In 

 what mode the bile contributes to the absorption of fat, is not yet 

 known. It certainly does not appear to act chemically, by decom- 

 posing or dissolving neutral fats; nor does it make, with oily matters, 

 a permanent emulsion. It probably co-operates with the pancreatic 

 juice. It has also been shown that fatty matters permeate moist ani- 

 mal membranes more readily than usual, if they be first wetted with 

 bile, or with an alkaline solution. Since provision is made in the 

 saliva and gastric juice, for the complete digestion of amyloid, gelati- 

 noid, and albuminoid substances, and, as we shall presently show, in 

 describing the action of the pancreatic juice, of fatty matters also, 

 the bile may be supposed to possess no exclusive digestive power, but 

 rather to be superadded, in order to complete some particular part of 

 the digestive process. 



As the contents of the upper part of the duodenum, like those of 

 the stomach, are strongly acid, whilst those of the small intestine 

 generally, become gradually alkaline in their descent, it was formerly 

 thought the bile, then regarded as a very alkaline fluid, was concerned 

 in neutralizing the acid of the chyme ; but it is now known that the 

 bile is but feebly alkaline, or sometimes even neutral, and the alka- 

 linity gradually acquired by the contents of the small intestine, is 

 attributed partly to the pancreatic and intestinal juices, and partly to 

 the evolution of ammonia, from slow decomposition. 



The bile not only imparts a bright yellow color to the chyme in the 

 duodenum, but it further appears to exercise an anti-putrescent action, 

 thus preventing, or retarding, a fetid decomposition of the contents 

 of the intestine; for, in the absence of bile from the alimentary canal, 

 these frequently become decomposed, causing flatulence and diarrhoea. 

 In experiments made with bile, out of the body, it is found that various 

 fermenting processes are arrested by that fluid. 



The coloring matter, with the cholesterin, and a certain portion of 

 the other constituents of the bile, are found, more or less altered, in 

 the residue of digestion ; but by far the larger portion of its charac- 

 teristic, conjugated glycocholic and taurocholic acids, is absorbed by 

 the mucous membrane of the intestine. These acids, when boiled with 

 hydrochloric or other acids, are decomposed into cholalic acid, on the 

 one hand, and glycocoll and taurin, on the other. The cholalic acid is 

 then changed into choloidinic acid, and this again into a resinoid sub- 



